Synchronizing means for the hands of clocks



Oct. AV AMEND, JR ETAL Filed April l1, 3942 2 Sheets-Sheet l Oct. 3, 1944. A, AMEND, JR, ErAL 2,359,458

SYNCHRONIZING MEANS FOR THE HANDS OF CLOCKS Filed April 11, 1942 y 2 Sheets-Sheet 2 Patented Oct. 3, 1944 SYNCHRONIZING MEANS FOR THE HANDS OF. CLOCKS Adolph Amend, Jr., Harrington Park,'-N, J.,V and Frank L. Eidmann, deceased, Alate ,of Princeton, N. J., by. Ethel I. Eidmann, executrix, Princeton, N. J.,'assignorsV to General Time Instruments Corporation, New York, N. Y., a corporation of Delaware Application April 11, 1942, Serial-No..438,578

12 Claims.

This invention relates tosynchronizing means for the hands of a clock, and in particular to an improved clock constructionwherein the rotation of one hand may be arrested until another hand has been rotated into a predetermined Iposition after which the two hands will rotatein synchronism with each other.

The preferred embodiment of this invention herein shown and described is applied to a clock driven byva synchronous electric motor, Vbut it is understoodl that this invention may be Vapplied to other types of clocks.

It is a practice `to provide certain clocks with a second hand, but in such instances it rrnay be readily observed that the second hand is not synchronized with the minute hand. -Thatis, when the minute 'hand points to the even minute, or overlies a-minute mark on the clock-dial, the second hand at that time is not necessarily passing "12 on the dial. Rather, it is frequently ahead or behind the pointl it should be, and often times, by as much as twenty or thirty seconds. This is due to the fact that the second shaft is not positively geared to the minute -sleeve in the manner that the minute sleeve is to lthe hour sleeve.

In order to permit the setting of the clock hands, a slippage must be interposed between the hand which' is -to be set and those hands Vor otherA parts of the clock mechanism which Vrotate at a greater speed. For instance, in the usual electric clock construction, the second hand `shaft is geared directly to the motor, andthe setting mechanism is geared directly to the minute sleeve. The minute sleeve is drivenfrom the second hand `shaft at a reduced rate of speed through a friction clutch so that'its position may be set manually without driving the motor or the s econd hand by such setting.

A :primary object of this invention is to provide improved means by which the position of the second hand of the clock is automatically corrected or synchronized with respect to the minute hand at predetermined intervals; and further, to provide synchronizing means. whichvdo not interfere with the setting mechanism rfor the minute hand.

Another object is to `provide meansV for locking a clock hand in a predeterminedyposition, and for unlocking it at a predetermined time, so that -its position thereafter is synchronized with the time.

Another object is to provide a simple and eilicent hand synchronizing device which maybe incorporated `into the` usual clock mechanism Yat small,y cost.

Still another `object is to provide an improved means for-associatingthe hands of a clock with the driving mechanism `so that after one hand has been set manually, another hand may be un- Adependently. and automatically set so that the two Vhands may thereafter rotate in synchronism. .-A still further object isl to provide, for a clock `or similar device, improved means for synchronizing the phase relationship of two elements "which rotate. at .different speeds.

. Other objects, features and advantages of this `.invention-.WillV appear as the description proceeds.

With reference to the accompanyingdrawings, in which vlike reference numerals designate like parts, Fig. 1. is. aV front elevation of a clock embodying a preferred form of this invention, the housing l being removed;

Eig. -2 lisi a side elevation of the clock shown in Fig.` 1;

`Fig. Sis-a section taken along line 3 3 of Fig. 2;

Fig. 4 is an enlarged section taken along line Fig. 5 Qis a perspective view of the synchronizingY mechanism; and

Figs. 6 to.9 inclusive are diagrammatic views showing the parts of the synchronizing mechanism at different times.

In vFigs. 1 vandv2, the .reference numeral I0 designates a-basev for the clock upon which base Vare mounted spacedplates II and. I2. The plates 4are secured to one another by means of the usual spacers I3 and one of the plates may be secured to the base I0 byfmeans of alug 20.

`A synchronouselectric motor I4 is secured to vthe rear face of thevplate I I, and the usual clock -dia1 I5 is providedin frontof the plate I2, and -may be secured thereto by means oi" suitable spacersfwhich are not shownherein. The clock :dial is provided/With the .usual indicia I6, and

ywith the usual hour, minute and second hands I1, I8 and I9, respectively.

-The plate I I is apertured so that amotor shaft 2| may extend therethrough, the motor shaft in this'instancebeing partially enclosed in a cylindrical housing-22, in the forward end of which the end of the-motor shaft 2I vfmaybe journalled. The side of the cylindrical housing 22 is out away to 4expose a driving pinion 23- whichmeshes with a^gear"24,-thisgear being mounted on a shaft 10- which is journalledin the plates I I and I2. A pinion '25, lsecured tothe gear 24,7drives a gear 26 and its associated pinion 21, both of which are mounted on a shaft 1|. The pinion 21 meshes with and drives a gear 28 which is rotatably mounted on a second shaft 29 to which the second hand |9 is secured.

A thrust bearing 36 is provided in the plate I l for the rear end of the second shaft 29, the shaft being supported toward its forward end by the usual minute sleeve 4| and hour sleeve 52, the latter being journalled in the plate |2 and the dial I5. The gear 28 is formed with a hub 3| thereon which is pinned to a sleeve 32 surrounding the second shaft 29. A disc 33 is secured to the sleeve 32 and a spider 35, or other suitable frictional driving element, is confined between the disc 33 and a disc 34 which is pinned to the shaft 29 so that the latter shaft may be rotated therewith. The gearing between the motor I4 and the second shaft 29 is so proportioned that the latter will be driven at a speed of one revolution per minute, The frictional coupling between the driving gear 28 and the second shaft permits the latter to be rotated independently of the driving mechanism or to be held stationary while the motor is operating.

A pinion 36 is secured to, or forms a part of the drive gear 28 and hub 3|, and meshes with a gear 31 which is mounted on a shaft 38 journalled in the plates I| and I2. A pinion 39 secured to the gear 31 drives a minute sleeve driving gear 4E] which is rotatably mounted on the minute sleeve 4I. Minute sleeve 4|, surrounding the second shaft 29, extends through the plate |2 and the dial |5, and carries at its outer end the minute hand I8. The gear 40 is positioned between the collar 42 mounted on the sleeve 4|, and a hub 44 which is pinned to the sleeve. A cam 43 is carried on the hub 44, and a dished washer 45 is confined between the minute sleeve driving gear 49 and the cam 43, and provides a frictional coupling between the two so that the minute sleeve 4I may be driven from the pinion 36 at a speed of one revolution per hour.

A pinion 46 is mounted on a hub 41 between the plate I2 and the dial I5, and is pinned to the minute sleeve 4|. A gear 48 and a pinion 50 are mounted on a stub shaft 49, the gear 48 meshing with the pinion l46, and the pinion 56 meshing with and driving an hour sleeve driving gear The latter gear is mounted on a hub 53 which is pinned to an hour sleeve 52. This sleeve surrounds the minute sleeve 4I and carries at its forward end the hour hand I1. The gearing is so proportioned that the hour sleeve is driven.

from the minute sleeve 4| at a rate of onetwelfth of a revolution per hour.

A setting shaft 54 is journalled in the plates II and I2, and carries at its forward end a pinion 55 which meshes with the gear 48 so that the position of the minute and hour sleeves may be shifted with respect to the minute sleeve driving gear 46. A knurled knob 56 is provided at the rear end of the setting shaft 54 to facilitate the setting operation.

It will be seen that the synchronous electric motor drives the hands at their proper speeds, but that the frictional coupling between the minute sleeve and the motor permits the setting of the hands, The frictional coupling between the second shaft 29 and the motor permits the second hand to be locked in a predetermined position, by means hereinafter described, while the clockwork drives the minute and hour hands.

A washer 51 is disposed between the sleeves cassa/152% 4I and 32, and fits into a groove on the second shaft 29 so as to prevent displacementI of the shaft to theleft, as shown in Fig. 4. The thrust bearing 30 prevents displacement to the right. The axial position of the minute sleeve 4| is determined by the hub 44 which is pinned to it, and by the elements 42 and 40 which are confined between the hub 44 and the plate I2. The axial position of the hour sleeve 52 is determined by the hub 53 which bears against the rear surface of the clock dial I5, and which is confined between such surface and the hub 41. which is pinned to the minute sleeve 4I. A spacer 58 may be provided between the pinion 46 and the plate I2.

The means for locking in a predetermined position the second shaft 29 and its associated second hand I9, are shown in Figs. 2, 3, and 5, and comprise an arbor 60 which is journalled in the plates II and I2. The arbor carries two arms 6| and 62 which extend downwardly into the proximity of the disc 34 and the cam 43 respectively.

The end of the arm 6| is bent over to provide a locking detent 63 which is adapted to drop into a slot 66 formed in the periphery of the disc 34 to lock the same in a position wherein the second hand points to 12 on the dial. A coil spring urges the locking detent towards the disc 34 so that it will drop into the slot 66. The end of the arm 62 is bent over to form a cam rider 64 which cooperates with the cam 43 to control the action of the locking detent. The cam 43 is in the form of a disc which is provided with a notch 61. As the cam rotates once per hour, the rider 64 is displaced outwardly against the bias of the spring by its periphery during 59 minutes of each hour so that the locking detent is rendered inoperative. During the 60th minute, however, the notch 61 is opposite the cam rider 64 and the locking detent rides on the periphery of the disc 34 and drops into the slot 66 when the second hand arrives at its predetermined synchronized position.

The trailing wall of the notch 61 forms a cam rise surface 68 which causes the detent 64 to be camrned out of the notch 61 just as the minute hand arrives at the 60th minute position underlying the position of the second hand. The latter is then free to be rotated by the motor through the friction spider 35. The advancing wall of the notch forms a drop surface 69 which releases the detent at the 59th minute. This wall is also sloping so that the minute hand can be set manually in either direction.

The effective width of the notch 61 is 6, which represents one minute or the time during which the disc 34 makes one revolution. Consequently, the detent 63 is operative, that is, it rides on the periphery of the disc 34, only during the 59th minute of each hour, and synchronization is effected only during this interval.

The term synchronized position as used herein in reference to the minute hand I8 and the cam 43 designates that position of those parts which corresponds chronologically to the time indicated by the second hand |9 when it is in locked position; and, as used with reference to the second hand and the disc 34, designates that position which corresponds chronologically to a predetermined position through which the minute hand will be rotated and in which synchronized position the second hand should be locked until the minute hand catches up with it, after which time both hands will rotate in Synchromsm.

VThe operation of the synchronizing mechanism is shown in Figs. 6 to 9, inclusive. In Fig. 6, it will be assumed that theposition of the cam 43 is that which represents fifty-nine minutes and iifty seconds after the hour. If the second shaft 29 were synchronized with the minute sleeve, the slot 66 would be disposed 60 in a counterclockwise direction from the locking lugs. This on time position is designated in Fig. 6 by a broken line. As shown in the drawings, however, the second hand I9, the second shaft 29, and the disc 34 are shown in a position which is ten seconds ahead of its synchronized position. In other words, the second hand is ten seconds fast. In this position of the parts the locking detent 63 rides on the periphery of the disc 34.

As the disc 34 rotates past the position shown in Fig. 6, the locking detent will drop into `slot 66, and the position of the parts at approximately one-half second later'is shown in Fig. 7. The disc 34 and the second hand are now locked against further rotation, and can not be rotated until the cam rider 64 is displaced outwardly by further rotation of the cam 43 through its synchronized position thereby causing the locking detent to be released, vThe detent 63 directly underlies the rider 64 and is not vvisible in these figures.

The position of the parts at fifty-nine minutes and fifty-five seconds after the hour is shown in in Fig. 8, in which the cam rider and the locking detent are being displaced outwardly by the cam surface B8.

In Fig. 9, at exactly sixty minutes after the hour, the position of the cam 43 and the minute hand I8 is such that the locking detent has been cammed out of the slot 66 completely, and the disc 34 and its associated parts are now free to rotate. At this time the second hand I9 points to the sixtieth second, and thehands are now synchronized, and will continue to operate in synchronism until the minute and hour hands are again set by therotation of the knob 56.

It is preferable to have the cam 43 of a diameter slightly greater than that of the disc 34 as shown in the drawings, or, in the alternative, to so shape the arm 6I that there will be a slight clearance between the locking detent 63 and the periphery of the disc 34 during normal operation. This eliminates any drag on the disc 34, which might possibly cause the spider 35 to slip.

When the parts are synchronized, the locking detent 63 will not drop into the slot 66, except to that slight extent which is permitted by the sloping surface 68 when it is in a position onetenth of a degree in a counterclockwise direction from that shown in Fig. 9.

Another cam and cam rider may be added which rotates at a faster speed than the cam 43, if it is desired to secure greater accuracy, or one which rotates at a slower speed if it is desired to effect synchronization at less frequent intervals.

It will be noted that the preferred embodiment of this invention herein shown and described effects synchronization of the second hand with respect to the minute hand. Synchronization of the minute hand with respect to the second hand may be effected by mounting the locking disc on the minute Sleeve, and the cam on the second shaft. In this instance, the cam should be differently shaped so that its high portion extends only through 6. Furthermore, in this modification,the frictional coupling 45 is preferably weaker than'the frictional coupling 35 so that the former will slip more easily when the disc is locked. The second shaft may then be provided with independent setting means so that the second hand may be separately set to the correct second, after Which the minute hand will automatically drop back into synchronized relationship.

`It will be understood that various modifications and changes may be made in the preferred embodiment herein shown Without departing from the spirit of this invention. The description and drawings are intended to be illustrative only, and the invention is defined only by the appended claims.

We claim:

1. In a clock, a rotatable shaft, a hand secured to said shaft, time responsive driving means frictionally associated-with said shaft, and means to lock said shaft and said hand in a predetermined position against rotation bysaid vdriving means, another hand driven by said driving means, and means associated with said second mentioned hand to release said locking means when said second mentioned hand is rotated through a po sition wherein both of said hands are synchronized with respect to each other.

2. A hand synchronized clock comprising two hands which rotate at different speeds, means for locking one of said hands in a predetermined position, and means actuated during rotation of the other of said hands through a predetermined position to cause saiddetent means to be released.

3. A hand synchronizing device for a clock having two hands which rotate at diiferent speeds comprisingV a slotted disc associated with one of said hands, detent means adapted to drop into the slot of said disc to lock said disc ina predetermined position, and means actuated during rotation of the other of said hands through a `predetermined position to cause said detent means to be released.

4. A hand synchronizing device for a clock having two hands driven at different speeds comprising locking means associated with one of said hands to cause it to be locked in a predetermined position, and a cam associated with said other hand to release said vlocking means when said other hand is rotated through a position which is synchronized with respect to the predetermined position in which said rst mentioned hand is locked.

5. A hand synchronizing device for a clock having two hands driven at different speeds comprising locking means associated with one of said hands to cause it to be locked in a predetermined position, and means associated with the other of said hands to permit the operation of said locking means only during a predetermined period immediately prior to the rotation of said second mentioned hand through a synchronized position, said means engaging said locking means at other times in order to maintain said locking means inoperative.

6. A hand synchronizing device for a clock having a minute hand and a second hand, comprising a slotted disc associated with said second hand and a cam associated with said minute hand, a detent cooperating with said slotted disc to cause the same to be locked in a predetermined position, and means cooperating with said cam to cause said detent to be disengaged from said slotted disc when said cam rotates through.

a synchronized position corresponding to said predetermined position in which said disc has been locked.

7. A hand synchronizing device for a clock having a minute hand and a second hand, comprising common driving means for said hands, frictional couplings between each of said hands and said driving means so that the position of either hand may be shifted with respect to the other, a slotted disc associated with said second hand, a cam associated with said minute hand, a detent cooperating with said slotted disc, a spring for urging said detent against said slotted disc to cause the same to be locked against further rotation after it has been rotated into a predetermined position, and means actuated by said cam to cause said detent to be displaced against the bias of said spring so as to permit further rotation of said slotted disc after said cam has been rotated into a synchronized position with respect to the position of said disc.

8. In a clock having two hands rotating at different speeds, means to set manually the position of one of said hands, and means to set automatically the position of the other of said hands to correspond with the position of said rst mentioned hand, said means including a slotted disc associated with said second mentioned hand, a detent cooperating with said slotted disc for locking said disc and said second mentioned hand in a position which corresponds to a predetermined position through which said first mentioned hand will subsequently be rotated, and means operable by the rotation of said first mentioned hand through said predetermined position to release said detent.

9. A hand synchronizing clock comprising a second shaft, a driving gear rotatably mounted thereon, frictional driving means between said gear and said second shaft, a minute sleeve surrounding said second shaft, a driving gear rotatably mounted on said minute sleeve, frictional driving means between said latter mentioned driving gear and said minute sleeve, time responsive driving means for said driving gears, means to rotate said minute sleeve independently of said time responsive driving means to permit the setting of the minute hand with respect to said time responsive driving means, and means to synchronize the position of said second shaft with respect to said minute sleeve after the setting of the minute hand, said synchronizing means including a slotted disc mounted on said second shaft, a cam mounted on said minute sleeve, and means cooperating with said slotted disc and said cam to cause said second shaft to be locked in a predetermined synchronized position just prior to the time that said cam is rotated into a corresponding synchronized position, and to cause said second shaft to be released when said cam is rotated through said corresponding synchronized position.

10. A hand synchronizing clock comprising a second shaft, a minute sleeve, time responsive driving means, a gear train driven thereby including a second shaft driving wheel rotatably mounted on said second shaft and a minute sleeve driving wheel rotatably mounted on said minute sleeve, a friction clutch interposed between said second shaft driving wheel and between said second shaft, a friction clutch interposed between said minute sleeve driving wheel and said minute sleeve, slotted discs secured to said second shaft and to said minute sleeve respectively, and a pivoted member cooperating with said slotted discs and adapted to drop into the slotted portions of each simultaneously when said slotted portions are aligned with each other and with said pivoted member in order to blo-ck the rotation of the disc secured to said second shaft, the slot of the disc secured to the minute sleeve being of such a shape that said pivoted member will be rotated out of the slot of said second sleeve disc when said minute sleeve disc rotates through a synchronized position, and being of an effective width equal to the extent through which said minute sleeve disc rotates during a complete rotation of said second sleeve disc.

11. A hand synchronizing device for a clock y having a minute hand and a second hand comprising a rst disc constrained to rotate with said minute hand, a second disc constrained to rotate with said second hand, each of said discs being provided with slots in their peripheries, the slot of said first disc being of a width substantially equal to the distance through which said rst disc moves@ during a complete revolution of the second disc, and a pivoted member having portions biased towards the peripheries of each of said discs, the trailing wall of the slot in said rst disc being disposed at an angle to the motion of that portion of said pivoted member which is adapted to contact the same so as to cause said portion to be cammed out of said slot and to rock said pivoted member and the trailing wall of the slot in said second disc being disposed substantially parallel to the motion of that portion of said pivoted member which is adapted to contact the same so as to cause said second disc to be locked in a predetermined position when the slots of both discs are aligned with both of the contacting portions of said pivoted member and to remain locked until said pivoted member is rocked 'by said first disc.

12. A hand synchronizing device for a clock having a minute hand and a second hand comprising friction means for permitting movement of one hand without corresponding movement of the other hand, a notched disc constrained to rotate with said minute hand, a slotted disc constrained to rotate with said second hand, said notched disc being of a diameter greater than the diameter of said slotted disc, and a pivoted member biased towards said discs, and cooperating with said slotted disc to lock the same in a predetermined position if the second hand is not synchronized with the minute hand, said notched disc controlling the operation of said pivoted member to maintain the same disengaged from said slotted disc during fifty-nine minutes of each hour.

ADOLPH AMEND, JR. ETHEIL I. EIDMANN, Eecutrzw of the Last Will and Testament of Frank L. Ez'dmann, Deceased. 

